Originally, Red Hat’s enterprise product, then known as Red Hat Linux, was made freely available to anybody who wished to download it, while Red Hat made money from support. Red Hat then moved towards splitting its product line into Red Hat Enterprise Linux which was designed to be stable and with long-term support for enterprise users and ‘Fedora’ as the community distribution and project sponsored by Red Hat. The use of trademarks prevents verbatim copying of Red Hat Enterprise Linux.

Since Red Hat Enterprise Linux is based completely on free and open source software, Red Hat makes available the complete source code to its enterprise distribution through its FTP site to anybody who wants it. Accordingly, several groups have taken this source code and compiled their own versions of Red Hat Enterprise Linux, typically with the only changes being the removal of any references to Red Hat’s trademarks and pointing the update systems to non-Red Hat servers. Groups which have undertaken this include CentOS (the 8th most popular Linux distribution as of November 2011),[13] Oracle Linux, Scientific Linux, White Box Enterprise Linux, StartCom Enterprise Linux, Pie Box Enterprise Linux, X/OS, Lineox, and Bull’s XBAS for high-performance computing.[14] All provide a free mechanism for applying updates without paying a service fee to the distributor.

Rebuilds of Red Hat Enterprise Linux are free but do not get any commercial support or consulting services from Red Hat and lack any software, hardware or security certifications. Also, the rebuilds do not get access to Red Hat services like Red Hat Network.

Unusually, Red Hat took steps to obfuscate their changes to the Linux kernel for 6.0 by not publicly providing the patch files for their changes in the source tarball, and only releasing the finished product in source form. Speculation suggested that the move was made to affect Oracle’s competing rebuild and support services, which further modifies the distribution. This practice however, still complies with the GNU GPL since source code is defined as “[the] preferred form of the work for making modifications to it”, and the distribution still complies with this definition.[15] Red Hat’s CTO Brian Stevens later confirmed the change, stating that certain information (such as patch information) would now only be provided to paying customers to make the Red Hat product more competitive against the growing number of companies offering support for products based on RHEL. CentOS developers had no objections to the change since they do not make any changes to the kernel beyond what is provided by Red Hat.[16]

A number of commercial vendors use Red Hat Enterprise Linux as a base for the operating system in their products. Two of the best known are the Console Operating System in VMware ESX Server and Oracle Linux respin.

Most popular Linux Distributions

Android is the most popular Linux distribution ever; despite 99 percent of its users not realizing that they’re Linux users.